1. Field of Invention
The present invention relates to a polymer material, and an ophthalmic lens and a contact lens constituted with the same. More particularly, the present invention relates to a polymer material which has high oxygen permeability and is superior in water wettability and lubricity of the surface as well as flexibility, and which is suited for ophthalmic lenses and contact lenses.
2. Description of the Related Art
Silicone hydrogels have been used as a material and the like of ophthalmic lenses such as contact lenses owing to high oxygen permeability. However, since silicone hydrogels have low water wettability and lubricity of the surface in general, various efforts such as surface treatments, blending of a hydrophilic polymer and the like have been made in attempts to improve these regards.
Techniques for improving lubricity and water wettability of the surface of contact lenses produced using such a silicone hydrogel were developed which include: (1) a technique of blending polyvinylpyrrolidone that is a hydrophilic polymer in a mixture of monomer components (see PCT International Publication No. 01/70837); (2) a technique of soaking a contact lens in a stock solution containing a surfactant and hydrophilic polymers to allow the surfactant and the like to attach on the surface of the contact lens (JP-A No. S61-69023); (3) a technique of allowing surfactant molecules to be covalently bonded directly on the surface of the lens of a silicone hydrogel (see U.S. Pat. No. 4,546,123); (4) a technique in producing a contact lens constituted with a silicone-containing monomer and a hydrophilic monomer as monomer components in which the monomers are homogeneously dissolved by using a surfactant and/or an organic solvent as additive(s) (U.S. Pat. No. 4,534,916); (5) a technique of permitting containments of a surfactant in a polymer by bringing a polymeric substrate into contact with a mixture of a carrier liquid and an impregnating agent containing a surfactant in a supercritical fluid such as carbon dioxide gas (JP-TA (Translation of PCT Application) No. H8-506612); and the like.
However, in the aforementioned Prior Art (1), it is difficult to homogeneously dissolve a silicone-containing monomer having hydrophobicity and a hydrophilic polymer in a monomer mixture; therefore, favorable water wettability and lubricity for a contact lens cannot be easily attained. In addition, persistence of water wettability and lubricity of a contact lens for a long period of time is impossible in the aforementioned Prior Art (2). In the aforementioned Prior Arts (3) and (4), the amount of the surfactant used is comparatively great; therefore, the surfactant aggregated on the surface of the contact lens, and the surfactant contained within the contact lens are gradually released, thereby leading to failure in persistence of water wettability and lubricity for a long period of time, and possibility of occurrence of eye irritation during use of the contact lens.
Moreover, in the aforementioned Prior Art (5), since a surfactant that substantially poorly interacts with a polymer is used, the surfactant is likely to be eluted from the polymer in a solvent such as water or buffer, leading to failure in persistence of water wettability and lubricity for a long period of time. In addition, when the surfactant is contained in a polymer material of a contact lens or the like, the polymer material per se is likely to be deformed due to the behavior in incorporation and gradual release of the surfactant, resulting in a disadvantage of impaired stability.